1. Field of the Invention
The present invention generally relates to a shearing machine having a movable upper blade and a fixed lower blade for cutting or shearing sheet-like workpieces such as sheet metals, and more particularly the present invention pertains to the adjustments of the stroke of the upper blade and the horizontal clearance between the upper and lower blades.
2. Description of the Prior Art
As is well-know, shearing machines for cutting or shearing sheet-like workpieces such as sheet metals are provided with an elongated movable upper blade carried by a ram member and an elongated fixed lower blade which is fixedly provided under the upper blade to cooperate therewith. The ram member carrying the upper blade is so arranged as to be mechanically or hydraulically moved up and down to bring the upper blade into and out of engagement with the lower blade to cut or shear the workpieces. Generally, the ram member can be driven at a higher speed in the mechanically operated shearing machines than in the hydraulically operated shearing machines. Also, the ram member is moved straight up and down in what is called a guillotine-type shearing machine, and it is swung up and down around a pivot means in what is called a swing-type shearing machine. Generally, the swing-type shearing machines can be manufactured and assembled at lower costs than the guillotine-type shearing machines. Also, in order to cut or shear square-shaped blanks out of large sheet-like workpieces, there are shearing machines which are provided with L-shaped or right-angled upper and lower blades.
In shearing machines, a workpiece smaller in width than the length of the upper and lower blade can be cut or sheared by a single stroke of the upper blade to the lower blade. However, in order to slit a workpiece larger in width than the length of the upper and lower blades, it is necessary to continuously repeat the strokes of the upper blade to the lower blade with the workpiece being fed or moved little by little along the cutting edges of the upper and lower blades. Also, in order to slit wider workpieces in this manner, it is necessary to make an adjustment to set the lower limit of the stroke of the upper blade higher than in an ordinary shearing operation. Heretofore, there have been hydraulically operated shearing machines in which the adjustment can be made to change the lower limit of the stroke of the upper blade, but there have been no mechanically operated shearing machines in which the adjustment can be made for such purpose. Also, in the conventional hydraulically operated shearing machines, not only can the adjustment of the stroke of the upper blade not be accurately made, but also the ram member cannot be operated at higher speeds as described in the above.
In order to accurately shear the sheet-like workpieces in the shearing machines, it is further necessary to adjust the horizontal clearance between the upper and lower blades depending upon the thicknesses of the workpieces to be sheared. The clearance between the upper and lower blades is adjusted in various ways in the conventional shearing machines, but heretofore there have been no satisfactory clearance adjusting means for shearing machines having L-shaped or right-angled upper and lower blades. For instance, the clearance between the upper and lower blades is adjusted by tilting the ram member (as disclosed in U.S. Pat. No. 3,282,141), but the clearance adjusting device is complex, expensive and inconvenient.